This disclosure is related generally to control of air vehicles, and more particularly, to the automatic control of air vehicles during catapult launch.
Current aircraft use an Angle Of Attack based control system during catapult launch from an aircraft carrier. Angle Of Attack sensors have to be mounted externally on the aircraft. Accordingly, such sensors are subject to being damaged by the harsh aircraft carrier environment. Although multiple sensors can be mounted on the aircraft for redundancy, each sensor may provide different data because of sideslip and other factors. Furthermore, when a sensor fails, the signal from the remaining sensors are averaged, and a bad signal from one of the sensors gets averaged with the signals from the other sensors. Thus, only prompt and appropriate action by the pilot of the aircraft can control the aircraft in case of sensor failure.
A catapult launch control system for an air vehicle having a flight control system includes an inertial sensor system for providing a vertical rate of the air vehicle and a forward acceleration of the air vehicle. An altitude hold loop uses as input an altitude command and generates a vertical rate command. A vertical rate control loop uses as input the vertical rate command and the vertical rate to generate a vertical rate loop vertical acceleration command. A constant throttle airspeed hold loop uses as inputs an airspeed command and the forward acceleration to generate a constant throttle airspeed hold vertical acceleration command. A vertical acceleration command select loop uses the vertical rate loop vertical acceleration command and the constant throttle airspeed hold vertical acceleration command as inputs to provide a selected vertical acceleration command. The flight control system drives the air vehicle to the selected vertical acceleration command.
A method of controlling an air vehicle during catapult launch having a flight control system includes determining a vertical rate loop vertical acceleration command for the air vehicle to reach and maintain an altitude command. The determining of the vertical rate loop vertical acceleration command is based on inputs of a vertical rate of the air vehicle sensed by an inertial sensor system and an altitude of the air vehicle. The method also includes determining a constant throttle airspeed hold vertical acceleration command for the air vehicle to reach and maintain an airspeed command. The constant throttle airspeed hold vertical acceleration command is based on inputs of a forward acceleration of the air vehicle determined by the inertial sensor system and airspeed of the air vehicle. The method also includes determining a selected vertical acceleration command by selecting the maximum of the vertical rate loop vertical acceleration command or the constant throttle airspeed hold vertical acceleration command. The selected vertical acceleration command causes the flight control system to drive the air vehicle to the selected vertical acceleration command.